you can get the needed files from this directory:

   SA15OT.fits   - starting fits OT file
   SA15OTfull.fits - completed OT fits file
   input.data     - ascii catalog from wich SA15OT.fits is made
   headers.dat    - needed to make OT fits file
   stsdas2objt.cl - script to format OT files
   fix_it_1.cl    - runs other tasks for format OT files
   fmrgN20020413S0120_add.fits - SA15 I gmos image

Here is how I made my OT fits file:

tcreate SA15OT.fits headers.dat input.data

This makes a fits table that is not in the correct format for gmmns

I define the task 

   task stsdas2objt = stsdas2objt.cl

I load the gemini package in IRAF and then run the script:

  fix_it_1.cl

This gets the formats correct etc.

The in gmms I load the image:

fmrgN20020413S0120_add.fits 

and then load the OT under the GMOS_MMS button and "convert OT fits to catalog"
option.

That should do it.